Means for controlling the supply of feed water to boilers



J. SIM

Sept. 12, 1933.

MEANS FOR CONTROLLING THE SUPPLY OF FEED WATER TO BOILERS Filed July 25, 1932 Patented Sept. '12, 1933 a,

PATENT OFFICE MEANS FOR CONTROLLING THE SUPPLY OF FEED WATER TO BOILERS James Sim, Cathcart, Glasgow, Scotland, as-

signor .to G. & J. Weir, Limited, Glasgow,

Scotland Application July 25, 1932, Serial No. 624,558, and in' Great Britain September 30, 1 931 1 Claim.

The present invention relates tothe control of boiler feed pumps supplying feed water to boilers, especially water-tube or small-water-capacity boilers.

The controlling means according to the, present invention, which is directed to the control of the supply of feed water to a plurality of boilers served by a common turbine-driven feed pump, comprises a plurality of floats individual to the several boilers and each participating in" thechanges of the water level in the associated boiler, each float being arranged to operate a steam valve in a branch of the steam passage leading to the turbine and alsoa water valve interposed between the feed pump and the feed check valve of the respective boiler.

The steam valve and the water valve oper-' ated by each float may be disposed coaxially with the pivot of the float lever so as to'receive joint turning movements about the common axis.

The invention is illustrated by way of example in the accompanyingdrawing in which Fig. i is a part elevation part vertical section showing the feed arrangement for a group of boilers in which the boiler feed pump is driven by a steam turbine; Fig. 2 is a sectional plan view of the float chamber and steam and water valves.

Referring to Fig. 1, A denotes the steam drums of the steam boilers and B the feed check valves. With each of the three boilers there is associated ;a float housed in a float chamber or box D connected by pipes E'and F to the'respective boiler drum A so that the water level in the chamber D will at all times correspond to that in the boiler drum A connected thereto;

Each of the floats C operates both a steam throttle valve G and a water valve M interposed between the feed pump and the feed check valve B; or the water valve may be operated through the medium of a relay device.

The relation'of the steam and water valve openings is preferably such that. the water valve M lags behind the steam valve G during the closing period, i. e., on rising water level, andis in advance of the steam valve during the opening period, 1. e., on a falling water level. This arrangement entails the minimum pressure loss across the valve M and consequently the minimum'energy consumption of the feed pump.

The steam to the turbine fordriving the feed pump K is taken from the boilers A by the pipes H and passes through the three steam throttle valves G, and thence by way of the pipe connections J to the turbine. The water is discharged from the feed pump K through the main pipe L and branch pipes L. each. leading to its water valve M, and thence by way of the feed check valves to the several boilers.

A pressure regulator N is fitted on the steam inlet to the feed pump and connected by a small pipe to the feed pump discharge. This regulator acts by closing down the steam to the pump when the pump discharge pressure reaches a predetermined figure and thus prevents overspeeding of the pump, thereby meeting the contingency of the boiler feed check valves being inadvertently shut when the pump is being supplied with steam.

What is claimed is:-

The combination with a plurality of boilers, of a turbine-driven feed pump common to the several boilers, a steam main having connections to each boiler, a steam main having a connection to the turbine, parallel cross connections between said steammains, water pipe connections from the pump to the boilers, feed check valves, one for each boiler, intercalated said water pipe connections, floats individual tothe several boilers and each participating in changes in water level in the associated boiler, levers, one operated by each float, steam valves interposed in said parallel cross. connections, and water valves interposed in said water pipe connections between said feed pump and said feed check valves, each float operating a steam valve and a water valve for its associated boiler, the steam valve and 

